We Give Power To Words

If I said "I like you", you might be happy (you might also be creeped out, but let's assume it would make you happy). If I said "I love you", you might have a significantly stronger reaction (whether it is positive or negative). So why is it that "like" and "love" have such different levels of power?

Because they mean different things.
Yes, like and love mean different things, but the point is, who determines what a word actually does mean?

Society determines it. Words already have meanings when we're born.
That's a fair point, but it's not entirely accurate. There are two examples of this.  The first is that, if you track the history of language, you will find that some words have very drastically changed their meanings over the years, so words can change meaning, despite what they meant when you were born.

The second example is the word "love". There is a saying, "If you ask one hundred people for their definition of love, you will get one hundred different responses." This word has different meanings for different people. And, in fact, each person tends to have several meanings for that word. When people say "I love my mom", they do not mean it in the same way as when they say "I love lasagna."

So what does this mean? It means that we give power to words. It means that, although there are social influences, every individual person decides what a word means in general, and that the interpretation of a word can change based on the context of its use (who said it, why it was said, how it was said, etc.). As a writer, always be aware that the words you put down may convey what you intend, but if the reader interprets your words differently, your message may still be lost. Be very careful and very clear with your words and you will keep such happenings to a minimum.